The present invention relates to a technology for notifying events to a managing apparatus that manages network devices making up a network.
A network management system comprises managing agents that manage individual network devices and a managing apparatus that collects information from these managing agents. In this architecture the state of the network is checked and managed by a single managing apparatus accessing a plurality of managing agents or by the managing apparatus receiving events issued voluntarily from the managing agents.
As for the event issuing control on the part of the managing agents, the Recommendation X.734: Information Technology—Open Systems Interconnection—Systems Management—Part 5: Event Report Management Function specifies an event forwarding discriminator as the standard of the International Telecommunication Union—Telecommunication (ITU-T). The event forwarding discriminator decides whether or not to notify an internal event or state change notification within a network device received by the managing agent to the managing apparatus under a certain condition. The conditions of the event forwarding discriminator include time and network resources to be issued.
JP-A-5-75608 proposes a technology whereby the managing agent creates an event forwarding discriminator for each management function of the managing apparatus to simplify the event processing on the part of the managing apparatus and transmits an event required by the management function.
JP-A-10-336276 proposes a technology whereby a function to monitor event filtering processing is provided in the managing apparatus and, when the load of the managing apparatus increases, the filtering condition is changed and the event is notified to a managing application while keeping the event processing under a certain load.
In a managing system that manages a network to offer a variety of network services to a plurality of users, it may become necessary to manage network paths of individual users of the network in addition to the management of the entire network centering on the checking of the network configuration and the monitoring and control of traffic among network devices.
In such a case, in addition to forwarding the state of a device object itself it is also necessary to know the states of resources used to configure the network paths of the users. This increases the amount of information that needs to be reported from the device object to the managing apparatus, increasing the number of events forwarded from each managing agent. Hence, if the managing agents perform the event filtering and the transmission control, this reduces only the number of events reported from each managed object. Because the managing agents are not aware of the capability of the managing system and how many events are being reported from other managed objects, there remains a possibility that the total number of events issued from all managed objects may exceed the number of events that can be handled by the managing apparatus.
For the same reason, even if the filtering is controlled by the managing apparatus, when the total number of events notified from the managing agents is large, the filtering function can only perform simple processing at all times, which does not make sense.
The similar problems occur not only when the management requests diversify but also when the size of the network to be managed increases or when the managing apparatus becomes complicated due to changes made to the configuration of the network devices. Generally, a failure that occurs in the network affects a plurality of managed objects, so the managing apparatus receives events from all the affected managed objects at the same time. Therefore, as the network increases in size, the number of network devices as the managed objects increases. This in turn increases the total number of events that need to be processed by the managing apparatus even when the number of events reported from each managed object is small, with the result that the total number of events may exceed the event processing capability of the managing apparatus. Furthermore, as the network devices become complex, the number of events representing their behaviors also increases, which means that the number of events reported from each device increases, giving rise to a possibility that the total number of events may exceed the event processing capability of the managing apparatus.
Further, when the managing system performs individual management according to the requests from the network users, the network resources used by the user must be managed for different management requests. This means that the events reported from the network devices have different levels of importance depending on the user management requests even when the events are of the same kind from different resources. This requires processing which ensures that the managing apparatus receives an event with a higher level of importance. The conventional event control performed by the managing agents is the event filtering that only determines whether or not to send an event report to the managing apparatus and does not include a priority transmission control that discriminates between events of the same kind that have occurred simultaneously.
Therefore, when events more than the event handling capability of the managing apparatus should occur, there is a possibility that an important event, if it is sent to the managing apparatus, may not be able to be received by the managing apparatus.
Another possibility is that the functions and services provided by the network management system may no longer be guaranteed.